The Olivet Discourse

When messiah said "this generation" in the Olivet discourse, he meant the generation contemporary with himself.  That age of men then living.

Therefore, all the prophecies in the Olivet discourse are fulfilled in the 1st century.

Matthew 24:34 (KJV)  Verily I say unto you, This generation shall not pass, till all these things be fulfilled.

This generation.....

Matthew 11:16 (KJV)  But whereunto shall I liken this generation? It is like unto children sitting in the markets, and calling unto their fellows,

Matthew 3:7 (KJV)  But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come?

Matthew 23:33 (KJV)  Ye serpents, ye generation of vipers, how can ye escape the damnation of hell?

Matthew 12:34 (KJV)  O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.

Matthew 12:39 (KJV)  But he answered and said unto them, An evil and adulterous generation seeketh after a sign; and there shall no sign be given to it, but the sign of the prophet Jonas:

Matthew 12:41 (KJV)  The men of Nineveh shall rise in judgment with this generation, and shall condemn it: because they repented at the preaching of Jonas; and, behold, a greater than Jonas is here.

Matthew 12:42 (KJV)  The queen of the south shall rise up in the judgment with this generation, and shall condemn it: for she came from the uttermost parts of the earth to hear the wisdom of Solomon; and, behold, a greater than Solomon is here.

Matthew 12:45 (KJV)  Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first. Even so shall it be also unto this wicked generation.

Matthew 16:4 (KJV)  A wicked and adulterous generation seeketh after a sign; and there shall no sign be given unto it, but the sign of the prophet Jonas. And he left them, and departed.

Matthew 17:17 (KJV)  Then Jesus answered and said, O faithless and perverse generation, how long shall I be with you? how long shall I suffer you? bring him hither to me.

Matthew 23:35-36 (KJV)  That upon you may come all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias son of Barachias, whom ye slew between the temple and the altar.
Verily I say unto you, All these things shall come upon this generation.

Mark 8:38 (KJV)  Whosoever therefore shall be ashamed of me and of my words in this adulterous and sinful generation; of him also shall the Son of man be ashamed, when he cometh in the glory of his Father with the holy angels.

Mark 9:1 (KJV)  And he said unto them, Verily I say unto you, That there be some of them that stand here [this generation], which shall not taste of death, till they have seen the kingdom of God come with power.

Mark 14:60-62 (KJV)  And the high priest stood up in the midst, and asked Jesus, saying, Answerest thou nothing? what is it which these witness against thee?
But he held his peace, and answered nothing. Again the high priest asked him, and said unto him, Art thou the Christ, the Son of the Blessed?
And Jesus said, I am: and ye [the high priest, and by extension this generation] shall see the Son of man sitting on the right hand of power, and coming in the clouds of heaven.

Luke 17:25 (KJV)  But first must he suffer many things, and be rejected of this generation.

Acts 2:40 (KJV)  And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation.

The "days of vengenace" was when Jerusalem was surrounded by armies. That was 70AD.

Luke 21:20-22 (KJV)  And when ye shall see Jerusalem compassed with armies, then know that the desolation thereof is nigh.
Then let them which are in Judaea flee to the mountains; and let them which are in the midst of it depart out; and let not them that are in the countries enter thereinto.
For these be the days of vengeance, that all things which are written may be fulfilled.

You can read all about the ill fated first surrounding of Jerusalem by Roman armies at the command of Cestius Gallus at this link.

https://josephus.org/warChronology2.htm

What about the supposed pivot point in Matt 24:35?

New heavens and earth in my understand is this age, the church age. As opposed to the old covenant age. We know this because it is described as the time when Yahweh will be our God and we will be his people. A time when he will dwell in us.

Revelation 21:1-3 (KJV)  And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.
And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband.
And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God.

It is confirmed this is the new covenant era by Paul.

2 Corinthians 6:16 (KJV)  And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people.

And again in Rev.

Revelation 7:15 (KJV)  Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.

And in Jeremiah.

Jeremiah 31:33 (KJV)  But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people.

And Ezekiel.

Ezekiel 37:26-28 (KJV)  Moreover I will make a covenant of peace with them; it shall be an everlasting covenant with them: and I will place them, and multiply them, and will set my sanctuary in the midst of them for evermore.
My tabernacle also shall be with them: yea, I will be their God, and they shall be my people.
And the heathen shall know that I the LORD do sanctify Israel, when my sanctuary shall be in the midst of them for evermore.

And in Hebrews.

Hebrews 8:8-11 (KJV)  For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah:
Not according to the covenant that I made with their fathers in the day when I took them by the hand to lead them out of the land of Egypt; because they continued not in my covenant, and I regarded them not, saith the Lord.
For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.

The church is definately the dwelling place of God.

Hebrews 12:22 (KJV)  But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels,

Do you see that? You have come, already, to mount Sion. Part of the heavenly Jerusalem. Past tense right? If its not visible then its obviously a spiritual city, mount and temple.

Jesus went to prepare the church. The temple is God's dwelling place. On conversion God dwells in us. Hence we are living stones that make the temple of the kingdom. We are the "rooms" in our father's house.

John 14:2-3 (KJV)  In my Father's house are many mansions: if it were not so, I would have told you. I go to prepare a place for you.
And if I go and prepare a place for you, I will come again, and receive you unto myself; that where I am, there ye may be also.

1 Peter 2:5 (KJV)  Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ.

The only conclusion possible is that the new heavens and new earth is the new covenant age.

Answering the objection:

"The gospel was not preached to the whole world."

Matthew 24:14 (KJV)  And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come.

Fulfilled...

Acts 2:5 ESV — Now there were dwelling in Jerusalem Jews, devout men from every nation under heaven.

Colossians 1:5-6 (KJV)  For the hope which is laid up for you in heaven, whereof ye heard before in the word of the truth of the gospel;
Which is come unto you, as it is in all the world; and bringeth forth fruit, as it doth also in you, since the day ye heard of it, and knew the grace of God in truth:

Colossians 1:23 (KJV)  If ye continue in the faith grounded and settled, and be not moved away from the hope of the gospel, which ye have heard, and which was preached to every creature which is under heaven; whereof I Paul am made a minister;

Romans 10:16-18 (KJV)  But they have not all obeyed the gospel. For Esaias saith, Lord, who hath believed our report?
So then faith cometh by hearing, and hearing by the word of God.
But I say, Have they not heard? Yes verily, their sound went into all the earth, and their words unto the ends of the world.

Romans 16:25-26 (KJV)  Now to him that is of power to stablish you according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began,
But now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting God, made known to all nations for the obedience of faith:

Acts 17:6 (ESV) ... they dragged Jason and some of the brothers before the city authorities, shouting, “These men who have turned the world upside down have come here also,

Acts 24:5 (ESV) For we have found this man a plague, one who stirs up riots among all the Jews throughout the world....

Rom 1:8 (ESV) First, I thank my God through Jesus Christ for all of you, because your faith is proclaimed in all the world.

1Thess 1:8 (ESV) For not only has the word of the Lord sounded forth from you in Macedonia and Achaia, but your faith in God has gone forth everywhere, so that we need not say anything.

1Tim 3:16 (ESV) Great indeed, we confess, is the mystery of godliness: ​​​​​​​​​​​​​​​​​​​​​​​​​He was manifested in the flesh, ​​​​​​​vindicated by the Spirit, ​​​​​​​seen by angels, ​​​​​​​proclaimed among the nations, ​​​​​​​believed on in the world, ​​​​​​​taken up in glory. ​​

Crysostom (AD375) – “Therefore He [Paul] addedmoreover, ‘And this gospel shall be preached in the wholeworld for a witness to all nations, and then shall the endcome,’ of the downfall of Jerusalem. For in proof thatHe meant this, and that before the taking of Jerusalemthe gospel was preached, hear what Paul saith, ‘Theirsound went into all the earth;’ and again, ‘The gospelwhich was preached to every creature which is underHeaven.’ Which also is a very great sign of Christ'spower, that in twenty or at most thirty years the wordhad reached the ends of the world. ‘After this therefore,’saith He, ‘shall come the end of Jerusalem.’ For that Heintimates this was manifested by what follows.”

Eusebius (AD325) – “Thus, under the influence of heavenly power, and with the divine co-operation, the doctrine of the Saviour, like the rays of the sun, quickly illumined the whole world; and straightway, in accordance with the divine Scriptures, the voice of the inspired evangelists and apostles went forth through all the earth, and their words to the end of the world.” (Book II, Ch.III.).

“Tradition assigns the following fields to the variousapostles and evangelists: Andrew is said to have labored inScythia; hence the Russians worship him as their apostle.Philip spent his last years in Hierapolis in Phyrgia.Bartholomew is said to have brought the gospel accordingto Matthew into India. The tradition concerning Matthewis rather confused. He is said to have preached to his ownpeople, and afterward in foreign lands. James Alphaeus issaid to have worked in Egypt. Thaddeus is said to havebeen the missionary to Persia. Simon Zelotes is said to have worked in Egypt and in Britain; while another report connects him with Persia and Babylonia. The evangelist John Mark is said to have founded the church in Alexandria.” (Lars P. Qualben, History Of The Christian Church)

Answering the objection:

"But Jesus didn't come"

Matthew 24:3 ESV — As he sat on the Mount of Olives, the disciples came to him privately, saying, “Tell us, when will these things be, and what will be the sign of your coming and of the end of the age?”

The word coming here is παρουσία parousia. Interestingly, Strong's Greek dictionary includes in its definition....."of Christ to punish Jerusalem".

Strong's Definitions: παρουσία parousía, par-oo-see'-ah; from the present participle of G3918; a being near, i.e. advent (often, return; specially, of Christ to punish Jerusalem, or finally the wicked); (by implication) physically, aspect:—coming, presence.

Let's look at other comings that are not physical comings.

Mark 12: 9– 10 What will the owner of the vineyard do? He will come and destroy the tenants and give the vineyard to others.

John 14: 18 I will not leave you as orphans; I will come to you. John 14: 28 You heard me say to you, “I am going away, and I will come to you.”

Revelation 3: 20 Behold, I stand at the door and knock. If anyone hears my voice and opens the door, I will come in to him and eat with him, and he with me.

Revelation 2: 5 (to the church of Ephesus) Remember therefore from where you have fallen; repent, and do the works you did at first. If not, I will come to you and remove your lampstand from its place, unless you repent.

Revelation 2: 16 (to the church of Pergamum) Therefore repent. If not, I will come to you soon and war against them with the sword of my mouth.

Revelation 2: 25– 26 (to the church of Thyatira) Only hold fast what you have until I come. 26 The one who conquers and who keeps my works until the end, to him I will give authority over the nations.

Revelation 3: 3 (to the church of Sardis) Remember, then, what you received and heard. Keep it, and repent. If you will not wake up, I will come like a thief, and you will not know at what hour I will come against you.

Revelation 3: 11– 12 (to the church of Philadelphia) I am coming soon. Hold fast what you have, so that no one may seize your crown.

Clearly Jesus "coming" was imminent to the 1st century church as below verses prove.

Matthew 10:22-23 (KJV) And ye shall be hated of all men for my name's sake: but he that endureth to the end shall be saved. But when they persecute you in this city, flee ye into another: for verily I say unto you, Ye shall not have gone over the cities of Israel, till the Son of man be come.

Hebrews 10:36-37 (KJV) For ye have need of patience, that, after ye have done the will of God, ye might receive the promise.
For yet a little while, and he that shall come will come, and will not tarry.

Matthew 16:27-28 (KJV) For the Son of man shall come in the glory of his Father with his angels; and then he shall reward every man according to his works.
Verily I say unto you, There be some standing here, which shall not taste of death, till they see the Son of man coming in his kingdom.

Matthew 26:63-64 (KJV) But Jesus held his peace. And the high priest answered and said unto him, I adjure thee by the living God, that thou tell us whether thou be the Christ, the Son of God.
Jesus saith unto him, Thou hast said: nevertheless I say unto you, Hereafter shall ye see the Son of man sitting on the right hand of power, and coming in the clouds of heaven.

James 5: 7– 9 Be patient, therefore, brothers, until the coming of the Lord. … 8 You also, be patient. Establish your hearts, for the coming of the Lord is at hand. 9 Do not grumble against one another, brothers, so that you may not be judged; behold, the Judge is standing at the door.

Philippians 4: 4– 5 Rejoice in the Lord always; again I will say, rejoice. 5 Let your reasonableness be known to everyone. The Lord is at hand;

Answering the objection:

"But the end of the world didn't happen"

Please note the parallels to Matt 24:3
Also note it is the end of the AGE (aeon) not the WORLD (kosmos)

Matthew 24:3 ESV — As he sat on the Mount of Olives, the disciples came to him privately, saying, “Tell us, when will these things be, and what will be the sign of your coming and of the end of the age?”

Mark 13:4 ESV — “Tell us, when will these things be, and what will be the sign when all these things are about to be accomplished?”

Luke 21:7 ESV — And they asked him, “Teacher, when will these things be, and what will be the sign when these things are about to take place?”

The question is not about the end of the entire world, the end of history.

It's about "these things" he just mentioned. The desolation of the temple and city.